Application Of Glass Micromodel In Testing And Evaluation Of Kinetic Hydrate Inhibitors

A novel method for testing low dosage hydrate inhibitors (LDHIs) and its comparison with conventional techniques is described in this paper. The method is based on monitoring gas hydrate crystal nucleation and growth in high-pressure glass micromodels. The set-up, equipped with a magnifying system, provides a unique opportunity of observing the impact of LDHIs on crystal nucleation and morphology. Two LDHIs are tested in the presence of THF, carbon dioxide, methane, and natural gases with the objective of correlating the THF results with other gases. The results demonstrate the effect of gas composition and hydrate structure on the performance of LDHIs. The tests are repeated in a conventional kinetic rig with the aim of correlating and up-scaling the micromodel results, as well as testing the inhibitors under simulated pipeline conditions. The kinetic rig is equipped with a motor stirrer, providing information on the rheology of the fluid systems before and after hydrate formation, by measuring the torque on the stirring shaft. This can be used to assess the transportability of the fluid system when hydrates form. The effects of the two kinetic hydrate inhibitors on the hydrate induction time and the morphology of gas hydrates have been investigated. The results show that the combination of glass micromodel and a conventional kinetic rig could provide an invaluable means for designing and testing of LDHIs for the challenges ahead to extend the application of LDHIs in deepwater operations.